1) Field of the Invention
This invention relates to green dyes, which can play an important role in color filters for display devices such as liquid crystal television sets or in color separation filters for image pickup tubes or color copying machines, and also to color filters. The present invention is also concerned with near infrared absorbers, which can play an important role in optoelectronics-related fields such as recording of information, image sensors and protective goggles, and also with optical recording media fabricated using the near infrared absorbers.
2) Description of the Related Art
Known conventional filters using a phthalocyanine compound include inter alia those disclosed in Japanese Patent Laid-Open Nos. 30509/1984, 249102/1985, 140902/1986, 254903/1986, 254904/1986, 6904/1989, 88505/1989 and 233401/1989.
Among such phthalocyanine compounds, water-soluble compounds containing one or more sulfonic groups are suited for coloring filters in which gelatin or casein is used as a base material, and have been employed in gelatin-base filters. These filters have, however, been used only to a limited extent due to the poor heat resistance and moisture resistance of the filters per se. The phthalocyanine compounds containing substituents at the .beta.-positions thereof, which are disclosed in Japanese Patent Laid-Open No. 233401/1989, are excellent in durability but are not sufficient in transmission characteristics. On the other hand, phthalocyanine compounds containing substituents at the .alpha.-positions, which are disclosed in WO 88/06175 and GB 2168372A, are accompanied by the drawback that they have poor solubility in resins and, to obtain a color density useful as a green filter, the film thickness of the filter must be increased. Further, their transmittance characteristics as green dyes are not sufficient.
Usage of phthalocyanine compounds as near infrared absorbers is widely known, for example, from Japanese Patent Laid-Open Nos. 209583/1985, 152769/1986, 154888/1986, 197280/1986, 246091/1986 and 39286/1987. The absorption ability of these phthalocyanine compounds was however not sufficient as they are prone to association. Optical recording media making use of one or more of such phthalocyanine compounds are, therefore, accompanied by drawbacks such as low reflectance at 780-830 nm and insufficient sensitivity and recording characteristics.